In industrial fields in which strict color reproduction is required, color reproduction of a subject corresponding to an illumination environment is required. Further, in a standard illumination environment, for example, a color temperature is 5000 K in the field of printing and 6500 K in HDTV (high-definition television), and varies with the fields of use.
In order to confirm tones of colors in such different fields of use, simultaneously displaying a plurality of images having different white point settings within one screen is required in a display device.
A display device which simultaneously displays a plurality of screens having different white point luminance and chromaticity within one screen when a luminance of a screen A which is a screen corresponding to a first video signal is for example 80 cd/m2 and a luminance of a screen B which is a screen corresponding to a second video signal is for example 70 cd/m2 will be described by way of example. Usually, in a display device having a multicolor backlight in which backlights for different colors are combined, adjustment of a luminance and chromaticity (e.g., luminance: 80 cd/m2 and color temperature: 5000 K) of a white point is performed by changing an optical output for a color of each backlight.
Thus, adjustment of the backlight to the luminance and chromaticity of the screen A having a highest set luminance and adjustment of a video signal for a screen group (screen B) having a lower luminance to be darkened is considered for easy implementation.
Further, technology for displaying two images on one screen based on a plurality of video signals is described in Patent Document 1 described below.